Como definir o locale pt_BR no Laravel 5.4

app.php

<?php
// config/app.php

/* ... */

/**
* PHP Locale
*/
'phplocale' => ['pt_BR', 'pt_BR.UTF-8'],

/* ... */

Kernel.php

<?php
// app/Http/Kernel.php

  /* ... */
  
protected $middleware = [
  /* ... */
  
  \App\Http\Middleware\LocaleSetup::class,
  /* ... */
];  

LocaleSetup.php

<?php
// app/Http/Middleware/LocaleSetup.php

namespace App\Http\Middleware;

use Closure;

class LocaleSetup
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        $phplocale = config('app.phplocale');

        // descomente se for salvar o locale na sessão
    	  // if(session()->has('lang')) {
    		//     app()->setLocale(session()->get('lang'));
    		//     $phplocale = session()->get('locale');
    	  // }

    	  setlocale(LC_TIME, $phplocale);

        return $next($request);
    }
}

web.php

<?php
// routes/web.php
/*
|--------------------------------------------------------------------------
| Web Routes
|--------------------------------------------------------------------------
|
| Here is where you can register web routes for your application. These
| routes are loaded by the RouteServiceProvider within a group which
| contains the "web" middleware group. Now create something great!
|
*/

Route::get('/', function () {
  $dia = date('d');
  $ano = date('Y');
  $diaSemana = ucwords(Carbon\Carbon::instance(new DateTime)->formatLocalized('%A'));
  $mes  = ucwords(Carbon\Carbon::instance(new DateTime)->formatLocalized('%B'));

  return "{$diaSemana}, {$dia} de {$mes} de {$ano}";
});